This invention relates to a disposable pull-on undergarment and more particularly to undergarment such as a disposable pull-on diaper, training pants or incontinent pants.
Japanese Patent Application Publication No. 1997-38134A describes a disposable pull-on undergarment comprising a liquid-pervious topsheet, a liquid-impervious backsheet and a liquid-absorbent core disposed between these two sheets so as to configure front and rear waist regions and a crotch region extending between these two waist regions wherein the waist regions are connected with each other in bonding zones extending along transversely opposite side edge portions of the respective waist regions and thereby a waist-opening and a pair of leg-openings are defined. In each of the bonding zones, a plurality of welding lines are intermittently arranged to be spaced one from another by a predetermined distance longitudinally of the undergarment.
To take off the used undergarment, the front and rear waist regions may be pulled in opposite directions to tear off the undergarment along the bonding zones from the waist-opening toward the leg-openings.
The undergarment is provided with circumferentially stretchable first elastic members bonded under tension to peripheral edge of the waist-opening and with circumferentially stretchable second elastic members bonded under tension to respective peripheral edges of the leg-openings. Circumferentially stretchable third elastic members are bonded under tension to the front and rear waist regions so as to extend across these waist regions.
Each of these elastic members has longitudinally opposite end portions and an intermediate portion. In the case of the first and second elastic members, the opposite end portions and intermediate portion are disposed between the top- and backsheets and intermittently bonded to inner surface of at least one of these sheets by means of adhesive. In the case of the third elastic members, the respective opposite end portions are disposed between the top- and backsheets and intermittently bonded to inner surface of at least one of these sheets by means of adhesive while the intermediate portion is intermittently bonded to inner surface of the backsheet by means of adhesive. The respective opposite end portions of these elastic members partially lie in the bonding zones. The intermediate portion of the third elastic members circumferentially extend across the core.
In the undergarment disclosed in the Publication, the opposite end portions of the firstxcx9cthird elastic members partially lie in the bonding zones and may prevent the used undergarment from being smoothly torn off along the bonding zones.
It is an object of this invention to provide the disposable pull-on undergarment designed to be smoothly torn off along the bonding zones.
According to this invention, there is provided a disposable pull-on undergarment having first and second waist regions opposed to each other and a crotch region extending between these two waist regions wherein these first and second waist regions are connected with each other in bonding zones extending along transversely opposite side edge portions thereof so as to define a waist-opening and a pair of leg-openings and wherein first elastic members being stretchable circumferentially of the waist regions are bonded under tension to peripheral edge of the waist-opening and second elastic members being stretchable circumferentially of the legs are bonded under tension to peripheral edges of the leg-openings.
According to this invention the first elastic members respectively have first opposite ends and first intermediate portions extending between the first opposite ends, respectively, and the first opposite ends are positioned and fixed at first zones defined immediately inside the bonding zones in a circumferential direction of the waist-opening.
According to one embodiment of this invention, the second elastic members respectively have second opposite ends and second intermediate portions extending between the second opposite ends, respectively, and the second opposite ends are positioned and fixed at second zones defined immediately inside the bonding zones in respective circumferential directions of the leg-openings.
According to another embodiment of this invention, at least one third elastic member lying below the first elastic members and being stretchable in the circumferential direction of the waist-opening is attached under tension to at least one of the first and second waist regions between the peripheral edge of the waist-opening and the peripheral edges of the leg-openings and wherein the third elastic member has third opposite ends and third intermediate portions extending between the third opposite ends and the third opposite ends are positioned and fixed at third zones defined immediately inside the bonding zones in the circumferential direction of the waist-opening.
According to still another embodiment of this invention, a peel strength between the first and second waist regions in the bonding zones is in a range of 4xcx9c40 N with respect to 25 mm, a longitudinal dimension of the bonding zone.